[jorjef]

If you can see the membrane that's good, it will eventually turn into the fleshie head of the frogspawn. The best way I can describe it is the membrane seals the skeleton head, like if you put a balloon over your finger tip, the balloon being the membrane/head and you finger the skeleton. The head of the skeleton should never be exposed to see a bare white skeleton. If it is really receded you will still see fleshie parts between the ribs on the top of the head, as long as they aren't floating loosely above the head and are tucked in tight you should be okay. I wouldn't think all the heads are splitting at same time. A picture would help.